1. Field of the Invention
The present invention relates to a power frequency converter for an electronic device mounted in an aircraft.
2. Description of the Related Art
As a power frequency converter for converting three-phase AC power source to single-phase power frequency, a control apparatus of a single-phase/three-phase conversion apparatus is disclosed in Japanese Patent Unexamined Publication No. 2005-160257 for example that can compensate a pulsation amount of a single-phase instantaneous power. However, this apparatus uses a method for preparing a converter without a smoothing capacitor. This causes power having a poor quality not suitable for an aircraft-level power frequency converter.
An electronic device mounted in an aircraft must use a power source to be used in an aircraft based on a specification determined for a device provided in an aircraft. Generally, in the case of an electronic device that is based on an electronic device developed for the market and that is subjected to a minor change for an electronic device mounted in an aircraft, a method is used to change the design of a power part so that the power part can be used for the power source of the aircraft specification. In the case of some electronic devices however, it is very difficult to adapt the electronic devices to a power frequency to be used in an aircraft. Although the power frequency of an electronic device mounted in an aircraft is different depending on the fuselage of the aircraft, the power frequency is recently as 6 to 13.3 times higher than a commercial power frequency and has a very wide frequency variation range of 440 Hz.
When an electronic device developed for a commercial application is subjected to a design change so as to be adapted for the power source used in an aircraft as described above, a minor change may be insufficient to adapt the electronic device to the power source to be used in an aircraft. For the device as described above, a power frequency converter for an electronic device mounted in an aircraft (hereinafter simply referred to as “converter”) is additionally prepared through which the power frequency is converted to the one based on a general commercial power specification to thereby allow the electronic device to operate stably. For example, FIG. 4 schematically illustrates the configuration of a conventional converter. FIGS. 5A-B schematically illustrate a conventional converter circuit. In the usage pattern as described above, some electronic device as a load device connected to the converter may cause an interference to the power source to be used in an aircraft of the supply side of the converter.
This interference is caused in the supply current to the converter due to the variation of the instantaneous power consumption of the load device. This interference is most remarkably caused when the load device is a single-phase AC power source. This type of interference does not occur in principle if the load device is a three-phase AC power source and is used in a balanced load status. However, the interference as described above in a power frequency converter for an electronic device mounted in an aircraft may deviate from a specification of Load Demand Variation specified by the aircraft power specification.